Compendium 1: Human Structure and Function - What is Life and Anatomical Terminology

Learning Outcomes and Course Objectives

Define the terms "anatomy" and "physiology."
Understand the different levels of anatomy and physiology.
Identify the purpose of the anatomical position.
Identify the characteristics used to assess whether an organism is alive.
Describe the six levels of organization of the human body and provide examples for each level.
Apply anatomical directional terms in descriptive sentences.
Identify the three planes in which the body or organs can be divided.
List and describe the three anterior cavities of the trunk.
Explain and identify the division of the abdomen into quadrants and regions, including the major organs within each.
Explain the necessity, location, and function of serous membranes lining body cavities.
Describe the properties of serous membranes.
Define "homeostasis."
List the specific characteristics of the anatomical position.
Use appropriate anatomical terminology for body planes, directional terms, and anatomical relations.

Key Terms in Human Structure and Function

Anatomical position: A standardized physical stance used as a reference point.
Lateral: Away from the midline of the body.
Anatomy: The study of the structure of the body.
Macroscopic: Visible to the naked eye (also known as gross anatomy).
Anterior: The front of the body.
Medial: Toward the midline of the body.
Biology: The study of life.
Metabolism: The sum of all chemical processes occurring in the body.
Body cavity: Fluid-filled spaces inside the body that hold and protect internal organs.
Microscopic: Structures too small to be seen without a microscope.
Caudal: Closer to the tail.
Molecule: A group of atoms bonded together.
Cell: The basic structural and functional unit of life.
Organ: A structure composed of two or more tissue types that perform common functions.
Cellular: Relating to or consisting of cells.
Organ system: A group of organs that cooperate to perform a common function.
Chemical: Relating to chemistry or the interactions of substances.
Organisation: The specific arrangement of body parts from simple to complex.
Coronal: A plane that divides the body into anterior and posterior parts.
Organism: Any living thing considered as a whole.
Cranial: Closer to the head.
Physiology: The study of the processes or functions of living things.
Deep: Away from the surface; internal.
Posterior: The back of the body.
Development: Changes an organism undergoes through time.
Prone: Lying face downward.
Diaphragm: A muscular partition separating the thoracic and abdominal cavities.
Proximal: Nearer to the point of attachment or the trunk.
Distal: Farther from the point of attachment or the trunk.
Reproduction: The formation of new cells or new organisms.
Dorsal: Toward the back.
Responsiveness: An organism's ability to sense changes and adjust.
Frontal: Another name for the coronal plane.
Sagittal: A plane dividing the body into right and left portions.
Growth: An increase in size or number of cells.
Superficial: Toward or on the surface of the body.
Homeostasis: The maintenance of a relatively constant environment within the body.
Superior: Above or higher than another structure.
Horizontal: Parallel to the ground; transverse.
Supine: Lying face upward.
Human biology: The study of humans from a biological perspective.
Tissue: A group of similar cells and the surrounding materials.
Inferior: Below or lower than another structure.
Ventral: Toward the belly.

The Nature of Life: Characteristics and Classification

Pre-workshop Activity: Dead or Alive

Determining life is not always straightforward. Life can be assessed based on specific biological characteristics. The following items were analyzed:

1. A green salad: Dead. Reason: It was once part of a living plant but no longer exhibits metabolic processes or reproduction.
2. An active wasp nest: Living. Reason: Contains active organisms performing growth, metabolism, and reproduction.
3. A penguin: Living. Reason: Exhibits all characteristics of life.
4. A bunch of red roses: Dead. Reason: Cut from the living plant; life processes have ceased.
5. An airborne virus: Living. Reason: Capable of replication and maintaining specific organisation within a host.
6. An iPhone: Never living. Reason: Does not possess biological characteristics such as metabolism or growth.

Six Main Characteristics of Life

All living organisms share these six fundamental characteristics:

Organisation: Specific relationships among the parts of an organism and how those parts interact.
Metabolism: All chemical reactions taking place in the organism, including energy release and use.
Responsiveness: The ability to sense changes in its external or internal environment and make adjustments.
Growth: Increase in size or number of cells.
Development: Changes an organism undergoes over time, including:
- Differentiation: Change from general to specific cell types.
- Morphogenesis: Change in the shape of tissues, organs, and the entire organism.
Reproduction: Formation of new cells or new organisms.

Levels of Organisation in the Human Body

The human body is structured in a hierarchy of complexity:

Chemical Level: The most basic level involving atoms and molecules. Examples: $\text{DNA}$ , $\text{RNA}$ , proteins, hormones, lipids.
Cell Level: The basic unit of structure and function. Examples: Smooth muscle cell, red blood cell, neuron.
Tissue Level: Groups of similar cells and their surrounding materials. Examples: Nervous tissue, connective tissue, muscle tissue, epithelial tissue.
Organ Level: Composed of two or more tissues functioning together. Examples: Lung, stomach, brain, heart.
Organ System Level: Groups of organs that function together for a common goal. Examples: Respiratory system, renal system ( $\text{urinary system}$ ), cardiovascular system.
Organism Level: Any living thing considered as a whole. Examples: Human, elephant, ladybug.

Topic 1: Homeostasis

Definition and Principles

Homeostasis: The existence and maintenance of a relatively constant environment within the body despite external changes.
Regulated Variables: Includes body temperature, blood pressure, $\text{pH}$ , glucose levels, carbon dioxide ( $CO_2$ ), and oxygen ( $O_2$ ).
Set Point: Homeostatic mechanisms maintain the body near an ideal normal point.
Normal Range: Small fluctuations occur above or below the set point; homeostasis is still maintained as long as the variable stays within this range.
Failure of Homeostasis: Can result in disease or death.

Case Study: Jesse’s Blood Sugar Scare

Subject: Jesse, an $18$ -year-old female.
Presentation: Blurry vision, extreme thirst, fatigue, frequent urination, and extreme hunger.
Context: Recently moved to Perth ( $5$ days prior). Major life change triggered signs and symptoms.
Medical History: Diagnosed with Type $1$ diabetes mellitus $5$ years ago.
Diagnosis: Lab samples confirmed hyperglycaemia (high blood sugar levels).
Immediate Treatment: Intravenous cannula for blood tests, insulin, and fluids.
Long-term Management:
- Lead by the endocrinology team.
- Continuous glucose monitoring.
- Insulin pump for automatic adjustments.
- Healthy eating plan.
- Regular physical exercise.
Multi-disciplinary Care Team: Emergency physicians, nurses, dietitians, diabetes educators, GP, phlebotomist, laboratory scientists, endocrinologist, exercise physiologist, pharmacist, pathologist, psychologist, counsellor, social worker, podiatrist, and optometrist.

Disturbances of Homeostasis

Minor Disturbances: Simple and easy to recover from using self-regulating mechanisms.
- Examples: Shivering when cold, sweating when hot, sunburn, temporary blood pressure increases during exercise.
Major Disturbances: Require medical intervention if the individual is to recover.
- Examples: Hyperglycaemia (requiring exogenous insulin), full-thickness skin burns, foreign bodies in systems, cancer, stroke, heart attack, or brain injury.

Topic 2: Anatomical Terminology and Referencing

The Anatomical Position

The standard reference point for describing the orientation and location of body parts. Features include:

Standing erect/upright.
Head and eyes facing forward.
Feet flat on the ground facing forward.
Arms straight by the side with forearms supinated (palms facing forward).

Directional Terms and Definitions

Superior: A structure above another/higher. Example: The liver is superior to the urinary bladder.
Inferior: A structure below another/lower. Example: The diaphragm is inferior to the heart.
Anterior: The front of the body. Example: The sternum is anterior to the heart.
Posterior: The back of the body. Example: The sacrum is posterior to the urinary bladder.
Dorsal: Toward the back. Example: The spinal column is dorsal to the sternum.
Ventral: Toward the belly.
Medial: Toward the midline of the body. Example: The heart is medial to the lungs.
Lateral: Away from the midline of the body. Example: The thumb is lateral to the little finger ( $5^{\text{th}}$ digit).
Proximal: Specific to limbs—closer to the point of attachment. Example: The knee is proximal to the ankle.
Distal: Specific to limbs—farther from the point of attachment. Example: The elbow is distal to the shoulder.
Superficial: Toward or on the surface.
Deep: Away from the surface; internal. Example: Body organs are deep to the skin.
Caudal: Closer to the tail.
Cranial: Closer to the cranium/head.

Trunk Cavities and Subdivisions

Major Trunk Cavities

Thoracic cavity: Separated from the abdominal cavity by the diaphragm.
Abdominal cavity: Enclosed anteriorly by abdominal muscles.
Pelvic cavity: Enclosed by pelvic bones.

Note: The abdominal and pelvic cavities are not physically separated and are often combined as the abdominopelvic cavity.

Specific Regions and Barriers

Diaphragm: The muscle separating the thoracic cavity from the abdominal cavity.
Mediastinum: The area separating the left and right sides of the thoracic cavity. It contains the heart, thymus, oesophagus, trachea, blood vessels, and nerves.
Abdominal Organ Contents: Stomach, intestines, liver, pancreas, spleen, and kidneys.
Pelvic Organ Contents: Urinary bladder, parts of the large intestine, and internal reproductive organs.

Abdominopelvic Quadrants and Regions

The Four Quadrants

Right Upper Quadrant ( $RUQ$ )
Left Upper Quadrant ( $LUQ$ ): Location of the spleen.
Right Lower Quadrant ( $RLQ$ ): Location of the appendix.
Left Lower Quadrant ( $LLQ$ )
Note: The urinary bladder spans both the left and right lower quadrants.

The Nine Regions

Right Hypochondriac: Contains part of the liver.
Epigastric: Contains part of the liver, stomach, pancreas, and major blood vessels.
Left Hypochondriac
Right Lumbar
Umbilical
Left Lumbar
Right Iliac
Hypogastric: Contains the urinary bladder.
Left Iliac: Contains part of the large intestine.

Clinical Applications

Organ Displacement: Organs can move due to pregnancy, central abdominal obesity, or abdominal tumour growth.
Trauma: A stab wound to the epigastric region may damage the liver, stomach, pancreas, or major blood vessels.

Anatomical Planes and Sections

Planes are used to section the body to view spatial relationships between internal organs.

Frontal or Coronal Plane: A vertical plane that separates the body into anterior (front) and posterior (back) portions.
Horizontal or Transverse Plane: A plane running parallel to the ground that separates the body into superior (top) and inferior (bottom) portions.
Sagittal Plane: A vertical plane that separates the body into left and right segments.
- Mid-sagittal (Median) Plane: Divides the body into two equal halves through the midline (e.g., through the nose).
- Parasagittal Plane: Divides the body into unequal left and right segments (e.g., through a shoulder).

Plane Intersection Examples

Brain and nasal septum: Mid-sagittal, horizontal, and/or frontal planes.
Both eyes: Horizontal and frontal planes.
Heart and liver: Frontal and sagittal planes.
Knee and hip joints: Para-sagittal (if looking at one leg) and frontal planes.
Both knees: Horizontal and frontal planes.
Brain and right shoulder: Frontal only.
Sternum and spinal cord: Horizontal and mid-sagittal planes.

Serous Membranes

Structure

These membranes line the trunk cavities and cover the organs within them. They consist of two layers:

Visceral Serous Membrane: Covers the actual organ.
Parietal Serous Membrane: Lines the wall of the cavity.
Serous Fluid: Found in the cavity between the visceral and parietal layers to reduce friction.

Specific Named Membranes

Pericardium (Heart):
- Visceral pericardium (on the heart surface).
- Pericardial cavity (contains fluid).
- Parietal pericardium (outer lining).\n* Pleura (Lungs):
- Visceral pleura (on the lung surface).
- Pleural cavity.
- Parietal pleura (lines the thoracic wall).

Bioscope Online Resource

Resource Description: An online learning tool developed at Curtin University featuring images of real human material from body donors.
Anatomy Online Compliance Quiz:
- Required by the Health Department of Western Australia.
- Demonstrates understanding of the responsibilities under the Anatomy Act.
- Authorisation gained is valid for $12$ months.
- Mandatory requirement to ensure images are treated with the utmost respect.
Functionality:
- Search specimens by unit (e.g., $HUMB1000$ ).
- Three-dimensional ( $3D$ ) context maps and rotation controls.
- Ability to view specimens in different planes (Frontal, Sagittal, Transverse/Horizontal).
- Detailed labels provide anatomical descriptions and optimal viewing angles.